基于双极性脉冲电压的水电导率仪控制系统的设计

介绍了一种智能型水电导率仪的测量原理及软硬件结构.仪器采用双极性脉冲电压作为电导率测量的激励源,较好地解决高纯水电导率测量中的极化效应和电容效应对测量结果的影响.该仪器可以实现量程自动换档,温度自动补偿,电导率超限报警,清洗池进水和放水自动控制等功能;同时系统还具有人机交互界面,数据存储,与上位PC机通信等功能.上位机软件采用LabVIEW编程,通过串口实现了电导率数据的实时采集和显示.     

基于神经网络的三角阈值判别法(TOD)设计

首先阐述了三角闽值判别法(TOD)在红外成像系统性能评价中的作用,探讨了一种利用神经网络代替人眼实现TOD自动测量的手段,提出一种简单有效的实现TOD自动测量系统的方法.该方法以全硬件方案来实现,体现了神经网络的并行机制,不仅能够从数据中自动提取标靶的特征,而且还能统计数据并进行自动处理,得出最终结论,实现自动测量的要求.     

一种液体电导率的测量系统

提出了一种基于ARM处理器的电导率测量系统的设计方案,ARM处理器S3C2410对采集的电流信号和温度信号进行处理,经温度补偿后得到固定温度下的电导率后送入液晶显示,给出了系统测量的修正办法.测试结果表明:该系统功耗低、性能稳定、扩展性强.     

基于VISA和Mint的微波暗室自动测量系统实现

建立了一套基于VISA和Mint的微波暗室自动测量系统,通过计算机控制矢网和转台以实现高效率的天线与RCS的微波暗室自动测量.在Visual C++开发环境下,运用多线程技术将矢网和转台结合,同时采用VISA和SCPI命令实现矢网的自动控制,采用Mint ActiveX控件技术实现转台的自动控制,该方法易于实现矢网与转台的高效同步.实测表明,该系统操作方便,测量效率、测量精度与自动化程度较高,所采用的控制方法有着较好的通用性和可拓展性,具有广阔的应用前景.     

基于89C51单片机的喷油校泵台调速系统设计

针对传统内燃机车柴油喷油校泵台调速系统存在的问题.提出了一种基于89C51单片机的新型校泵台调速系统,该系统可自动测量与控制主轴电机速度.由于该系统采用单片机和PC机通信,可方便实现主轴转速的设定和显示,简化电路设计,便于维护和检修,从而提高校泵台的可靠性.     

基于LabVIEW的低噪声放大器增益压缩自动测量

为实现低噪声放大器增益压缩特性的自动测量,提出了一种基于LabVIEW仪器控制实现的自动化测量系统设计方案,并完成了系统的软硬件设计。该系统的硬件部分由Agilent E4438C信号发生器、Agilent E4419B功率计以及GPIB总线和接口卡构成;软件部分使用LabVIEW图形化的编程语言设计开发了信号发生器和功率计的自动化控制程序,实现了两个设备之间的协同工作。该系统除了可以自动配置仪器工作参数、读取并显示测量结果外,还增加了数据记录和后期处理模块,可以同步显示测试数据和测试曲线,这大大扩展了原有仪器的测试功能。实验表明,该系统具有测量准确、自动化、节约时间、使用方便等特点。     

亚毫米波场分布自动测量系统的研究

研究一种采用反射镜扫描方法由微机控制的亚毫米波场分布自动测量系统.该系统和传统的移动探测器扫描的方法相比,其优点在于能够实时、快速、精确地自动测量和显示场分布图,并能免除由于探测器抖动所造成的误差和噪声,本文还用该系统对一些亚毫米波准光元件的场分布特性进行了測量.     

基于GB3442-82的集成运放参数测试仪设计

该系统基于GB3442-82标准测量运算放大器参数的原理,以单片机和FPGA组成的最小系统为控制核心,实现了测量集成运放参数的功能.通过程控放大和精密调整放大,系统不仅完成了VIO、IIO、AIO、KCMR的测量(误差分别为1%和±2 dB),还实现了BWC的测量和自动量程转换功能,并由键盘和显示器等人机交互界面,准确显示测量信息,扩展了触摸屏控制和打印功能.     

自动量程切换电压测量系统设计

电压测量是电子系统中不可或缺的一项技术,随着待测电压动态范围的急剧扩大,需要能实现量程自动切换的测量方法。提出一种自动量程切换电压测量系统的设计方法,该系统基于程控增益放大器器件,使用单片机控制其增益实现量程的自动切换。针对信道误差、温度漂移等问题,采用通道自校准技术,降低了信道对于测量的误差。通过对实际软硬件的测试表明,该系统能准确根据大小信号调整量程,并对系统及环境误差有一定的抗干扰能力。     

基于图像识别的立定跳远自动测距系统设计

目前市场上的立定跳远自动测距系统的种类较少,主要分为压力传感器测距、红外传感器测距.其所需传感器数量繁多,导致价格昂贵,且在测量过程中对仪器进行移动十分不便.针对该问题,设计了一种基于图像识别的立定跳远自动测距系统.该系统采用ARM微处理器为核心,外部接入射频识别、图像采集、报警提示等多个模块.以射频识别模块对用户身份进行检测,以高清高速自动对焦摄像头为图像采集设备,通过算法进行图像处理,实现成绩测量.实验表明:该立定跳远自动测距系统设计能够实现对用户立定跳远成绩的准确测量,系统稳定可靠,输出的成绩在理论误差范围之内.该自动测距系统具有低成本、低功耗的特点,能够应用在多种应用场合中.     

Measurement System for the Feeble Fluctuation of Liquid Electroconductivity

An easy and practical system of feeble fluctuation of liquid electrical conductivity is described.The system,which increases a precision on the three orders magnitude as compared with that of the recent domestic conductivity meter,is used to measure the feeble fluctuation of the conductivity by means of compensation and comparison,so that it solves,the problem of measuring the feeble fluctuation.     

浅谈溶液电导率的测量

在溶液电导率的测量中,常常由于电导率仪温度补偿不准引起测量误差,文章提出一种新的测量方法,减少了因温度补偿不准引入的测量误差.     

智能电导率仪的设计

智能电导率仪采用交流测量法来测量电导率。正弦激励的产生是通过阻抗测试芯片AD5933来实现的。AD5933输出的正弦激励加在电导池的电极上,AD5933可以计算出溶液阻抗经过傅里叶变换后阻抗的实部R和虚部I(结果保存在AD5933的寄存器中),然后再计算出校准系数A,就可以通过单片机计算出溶液的真实阻抗,进而计算出溶液的电导率。温度补偿电路测量溶液温度,用于修正温度对测量带来的影响。     

Distinguishability in impedance imaging

Impedance imaging systems apply currents to the surface of a body, measure the induced voltages on the surface, and from this information, reconstruct an approximation to the electrical conductivity in the interior. This paper gives a detailed discussion of several ways to measure the ability of such a system to distinguish between two different conductivity distributions. The subtle differences between these related measures are discussed, and examples are provided to show that these different measures can give rise to different answers to various practical questions about system design.     

Features of the mechanism of electrical conductivity of semiinsulating CdTe crystals

Temperature dependence of electrical characteristics of p-CdTe semi4nsulating single-crystals are studied, and substantial features of their electrical conductivity not described in available publications are revealed. The activation energy of the p-type conduction material close to the intrinsic one can be both lower and higher than the half-width of the band gap of semi conductor. The results of the analysis of statistics of electrons and holes based on the electroneutrality equation showed that the observed features of electrical properties of the material can be interpreted based on the specific features of compensation processes. The procedure of determining the ionization energy and degree of compensation of acceptors responsible for electrical conductivity of the material is suggested. It is shown that, in the limits of climatic temperature variations, inversion of the conduction type can be observed, and, as a consequence, the Schottky contact can disappear in the CdTe-based detector of the X-ay and γ radiation.     

Thermal Conductivity Measurement Methods for SiGe Thermoelectric Materials

A new technique to measure the thermal conductivity of thermoelectric materials at the microscale has been developed. The structure allows the electrical conductivity, thermal conductivity, and Seebeck coefficient to be measured on a single device. The thermal conductivity is particularly difficult to measure since it requires precise estimation of the heat flux injected into the material. The new technique is based on a differential method where the parasitic contributions of the supporting beams of a Hall bar are removed. The thermal measurements with integrated platinum thermometers on the device are cross-checked using thermal atomic force microscopy and validated by finite-element analysis simulations.     

新型电导盐密仪的设计与实现

为了防止高压输电线路污闪事故的发生,定期进行绝缘子等值附盐密度的测试,根据测试结果指导线路的清扫工作是非常重要的,针对这一问题,设计了基于双处理器电导盐密测量仪,详细说明了测量原理、硬件构成和软件的设计方法,该仪器能够在进行盐密测量的同时对其温度和电导率等几项技术指标同时进行测试,而且精度高,反映速度快,满足了实际测量的需要。     

Parameter identification and hysteresis compensation of embedded piezoelectric stack actuators

A novel method for the identification of embedded piezoelectric stack actuator parameters in combination with a real-time capable hysteresis compensation measure is presented. The presented algorithms are based on the Maxwell resistive capacitor model and are particularly useful for the identification of piezoelectric actuators embedded in a high-precision micropositioning system where the disassembly of the complete system for separate actuator identification is not recommended or not possible. The parameter identification can be performed in a fully automated way and enables the adaptation of the compensation routine to the changed circumstances (temperature difference, wearing of actuators) as well. The hysteresis compensation method proposed here does not require significant CPU or memory resources. It can be implemented as an additional task on the already existing controller or a low-budget FPGA. As an example, the proposed method was validated experimentally by the parameter identification and hysteresis compensation of the piezoelectric actuators incorporated in a commercially available hybrid micropositioning system. The achieved experimental results are in very good agreement with the theoretical ones.     

Fast nonlinear image reconstruction for scanning impedance imaging

Scanning (electrical) impedance imaging (SII) is a novel high-resolution imaging modality that has the potential of imaging the electrical properties of thin biological tissues. In this paper, we apply the reciprocity principle to the modeling of the SII system and develop a fast nonlinear inverse method for image reconstruction. The method is fast because it uses convolution to eliminate the requirement of a numerical solver for the 3-D electrostatic field in the SII system. Numerical results show that our approach can accurately reveal the exact conductivity distribution from the measured current map for different 2-D simulation phantoms. Experiments were also performed using our SII system for a piece of butterfly wing and breast cancer cells. Two-dimensional current images were measured and corresponding quantitative conductivity images were restored using our approach. The reconstructed images are quantitative and reveal details not present in the measured images.     

应用于磁控电抗器控制器的一种电能计量实现方案

磁控电抗器可以实现无功补偿的平滑调节,而其电能计量模块关系到整个磁控电抗器控制器的精度和性能。针对某实际工程中磁控电抗器控制器反应速度快、精度高以及处理数据量大的要求,设计了一个STM32F103RBT6单片机驱动ADE7878计量芯片以获取三相电各相电能参数的电能计量模块实现方案。从测试结果表明,此方案符合工程要求。